Ruby Slade enjoys spending time with Bojangles, a cairn terrier, as Donatello, a Great Dane, awaits his turn to visit her. (Susan Craton/The Enterprise)

Bill McCarthy came out to greet the two dogs before they got through the front doors of St. Mary’s Nursing and Rehabilitation Center in Leonardtown this month.

McCarthy couldn’t keep from smiling as he scratched Donatello’s ears and hugged the 160-pound Great Dane.

“Beautiful,” he said.

The smiles continued as Donatello and his owner, Jason Hardesty of Waldorf, and Bojangles, a 15-pound cairn terrier, and his owner, Marla Pyles of Hollywood, entered the center and mingled with residents, visitors and staff members as part of their work with Pets on Wheels.

Pets on Wheels is a nonprofit volunteer organization in Maryland through which volunteers and their pets make friendly visits to people in nursing homes, assisted-living communities, veterans homes and facilities for the physically and mentally disabled.

Most of the therapy animals are dogs, but there are also a few cats, and even a large tortoise. There have been ferrets, potbellied pigs and other animals in the statewide program.

They are there to make people feel happier.

Kim Simpkins, activity director and volunteer coordinator at St. Mary’s Nursing and Rehabilitation Center, said the Pets on Wheels volunteers and their animals have been visiting the nursing center for about 10 years.

“The impact they have is amazing,” Simpkins said.

Residents’ family members tell staff members that their relatives staying at the center ask them to bring dog treats, so they’ll have something for the therapy dogs when they visit.

As the temperament-tested Pets on Wheels animals go from room to room, they stop to receive a scratch on the head, spend time in a dog lover’s lap or just sniff around the room. Their presence prompts discussions about “dogs I have known” and questions such as “What is that breed of dog like?” For Donatello, there’s this question: “How much does that dog eat?”

Lisa Norwood of Calvert County serves as the Pets on Wheels coordinator for the Southern Maryland counties. The region is home to about 30 volunteers who visit people at five facilities in St. Mary’s County, five in Calvert, three in Charles County and 21 in Prince George’s County, Norwood said. The Prince George’s program has been active for longer than the other three.

Norwood would like to see those numbers increase. She is looking for area residents with even-tempered pets who would like to volunteer. She also would like to see more facilities participate in what she sees as a valuable program.

Pets go through a screening process before they are approved to participate in the program, and the owners are asked to commit to at least an hour of visits per month. In return, Pets on Wheels matches volunteers with facilities that requested the service and provides insurance for the volunteers, as well as marketing and fundraising for the program.

Norwood said there is a list of facilities in Southern Maryland that would like the service but don’t yet have any volunteers.

Hardesty said he learned about the program when his mother spent time in the rehabilitation wing of St. Mary’s Nursing and Rehabilitation Center and he saw what an effect the animals’ visits made.

“It’s something different,” he said of the volunteer work. “You bring a smile to someone else’s face.”

He said that even when they visit Alzheimer’s patients, who might be unresponsive, volunteers place the patients’ hands on a dog’s head. While the people might not quite smile, Hardesty said, it’s clear they are affected by the animal’s presence. “You can see it,” he said.

On April 1, Donatello and Bojangles worked the activity room at the nursing center. Bojangles won points with residents for sweetly sitting on laps to be cuddled, while Donatello amazed with his presence alone. His massive head was at eye level for those in wheelchairs and on hospital beds.

Barbara Russell was a little taken aback by Donatello’s size at first, but she said she loves the visits from the animals. “We all look forward to it,” she said.

The dogs enjoy it, too, the volunteers said.

“He loves it,” Pyles said of Bojangles. “When I put the [Pets on Wheels] vest on him, he waits by the door.”

The idea behind Pets on Wheels is to “lick loneliness,” Norwood said. “A lot of these people don’t get visitors, and they look forward to it.

“It’s nice to bring a smile to someone’s face, even if it’s for only a couple of minutes.”